vapor lock?

[TerraJeep]

can someone help? I was driving yesterday (approx. 100F up I70) when liquid gas starts shooting out of the filler tube. I pull over and try to take of the gas cap and it takes 10 minutes to vent before I could take the cap off w/o it shooting across the parking lot.

it is a 94 YJ w/ 4.0. never had this problem before. I used to have a 79 cherokee that had v-lock, but the result was that it quit running. Yj still ran fine albeit with a lot less gas.

I have put a new cap on - hoping that it will vent.

ideas?

[spitfire]

Is there another kind of gas that people put in there vehicles other then liquid gas.

[TerraJeep]

ha ha - thanks for the comment. It is meant to imply that it wasn't just vapor pouring out of the closed cap, but liquid gas being forced out of the opening.

anyone with something helpful?

[Sequel]

Should the fuel system vent? I thought fuel injection requires a pressurized fuel system.

[TerraJeep]

Yeah, it is pressurized, but when the vapor is not getting to the injectors it back pressures to the tank. Fixed volume of space with an increasing volume of gas pressure is bad - so the excess pressure is made to release through venting gas caps.

has no body else had this problem?

[TerraJeep]

anyone

[Shoowallagager]

I had something that felt like vapor lock. I was driving back from Salt Lick City in about 100 deg weather. Didn't notice anything until I went up some steep grades and had to downshift. There was a loss of power that "felt" fuel related. I have a one year old fuel filter, tune up a few months ago and I wasn't able to pull any codes from the computer. It runs fine now, but I don't know what caused this. Shouldn't fuel injection pressurize the system enough to prevent vapor lock? When I floor the throttle, shouldn't the increased fuel flow cool the fuel lines? or does the increased load and heat overcome this. I did a small search and couldn't find anything relevant.

[wcjp]

How full was the tank? Could just be expansion. On the trail last week a guy with 93'Ford 1ton gear including the fuel injected 460 had vapor lock issues. Out of 19 various vehicles he was the only one. He was also the only one using Arco Gasoline. We think the alcohol had evaporated.

[Ron90YJ]

I had vapor lock issues while moving to WA, while in CO and MT because of the oxygenated gas-ahol. Vapor lock is caused by the fuel in the lines boiling and it being a in gas not liguid form. When you stop and the lines cool the gas returns to liquid and you can drive again. If you run Gas-ahol it happens more often and Arco gas is of that type. What others have said about the pressurization of your fuel tank is probally right. Vaporized gas will return to the tank.

[Shoowallagager]

My tank was half full, or is that half empty.

[TerraJeep]

my tank was pretty full when it began, but then after it started shooting out of the filler tube - it went to half empty.
the new cap seems to help, but it hasn't been that hot since and I have been driving it less in the last few days.
next cheap fix-attempt is to clean the fuel lines, better gas and hope for the best.
eventually, i need to pull the tank and do the whole thing - new fuel filter, pump, seal, etc. not happy to pull the tank